There are these peel-like products you can apply to your heels (I had one, but don't know the name now, but check out a beauty supply shop, and they'll have something). Use a file/loofah bar and scrub. Then, apply lotion. It's nice to soak your feet in hot water beforehand, too. http://shoes.about.com/od/foot_pain/a/cracked_heels.htm
There are a couple of different things that you can try to get rid of cracked heels. You can put some really strong lotion on your feet at night and put some socks on to ensure that it stays on the feet. There is special formula that you can put on them that is sold in most major stores.
Put shampoo on your heels and let it sit for about 5 minutes, then scrub your heels with a pumice stone. The shampoo softens the skin making it easier to get rid of the dry cracked skin. When you go to bed every night, put on lotion with shea butter and soft thick socks to keep the moisture in.